Apparatus comprising a fastening device



May 15, 1956 J. BERGMANS ETAL APPARATUS COMPRISING A FASTENING DEVICE Filed April 18, 1951 i a ma 1 5 5 53.2 4 ,4 6 ll ll! 6 a a AGENT United States Patent APPARATUS COMPRISING A FASTENING DEVICE Jan Bergmans and Engelbert Wiegman van Heaven, Ijlindhoven, Netherlands, assignors to Hartford National Bank and Tnrst Company, Hartford, Conn., as trustee Application April 18, 1951, Serial No. 221,696

V Claims priority, application Netherlands May 31, 1950 2 Claims. (Cl. 248358) This invention relates to a fastening device for securing to another body electrical apparatus, such as transformers, chokes or the like. In particular, these electrical apparatus, when energized, havetwo points thereon which perform motions of equal but opposite amplitudes along a line connecting the two points, the fastening device being secured to the apparatus at these two points and supporting said apparatus in a position spaced from the supporting body.

During operation, such apparatus produce oscillations which are transmitted via the fastening device to the body to which the apparatus is secured, which oscillations may be radiated by this body as sound oscillations.

The object of the invention is to reduce the transmis sion of oscillations from the apparatus to the said body, preferably to the value of zero.

According to the invention, an electrical apparatus having two points which perform motions of equal and opposite amplitudes on the line connecting the points when the apparatus is energized is provided with a fastening device for securing the apparatus to a supporting body. The fastening device comprises at least one substantially U-shaped element having two limbs of equal lengths converging towards each other interconnected by a transverse member, the ends of the limbs being secured to the said points of the apparatus. The rigidity of the limbs and that of the transverse member are related to one another and to the angle of convergence of the limbs in a manner such that the variation of the distance between the center of the transverse member, which is to be fastened to the supporting body, and the line of connection between the said points is less than A or /50 of the amplitude of the motion of the said points, and preferably is zero.

The angle between the limbs, i. e., the angle at the intersection of the extended planes of the limbs, preferably lies between 20 to 40.

In order that the invention may be more clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying diagrammatic drawing, given by way of example, in which:

Fig. 1 is a side view of a transformer and a fastening device secured thereto.

Fig. 2 is a sectional view taken in the plane IIII of Fig. 1, and

Fig. 3 shows diagrammatically the manner in which deformation of the U-shaped element may take place during operation of the transformer.

The ferromagnetic part of the transformer is constituted by sheet iron layers held together by means of bolts 1. On the central horizontal limb 2 of the ferro-magnetic part are provided the windings of the transformer. These windings are designated 3 in Fig. 1, and are omitted from Fig. 2. By means of the bolts 1 two substantially U-shaped stay straps 4 are secured each at each end of the transformer one to one side and the other to the 2,745,623 Patented May 15, 1956 other side of the bolted layers. Each stay strap 4 comprises two limbs 5 converging towards the open ends of the limbs 5 and interconnected by a transverse part 6 not in contact with the transformer. The bolts 1 pass through apertures provided in lugs 7 at the open ends of the limbs 5. Feet 8 are provided one at the center of each transverse part 6 and at right angles thereto, each foot 8 being provided with an aperture 9 for securing the apparatus to another body, for example, to the fitting of a gas-discharge lamp.

In the present case, the bolts 1 represent the points of application of the fastening device comprising substantially U-shaped elements to the transformer. During the operation of the transformer, in its elastically suspended condition, these points of application perform at any moment relatively opposite motions in an outward direction of equal amplitudes in the plane through the axes of the bolts 1. These motions are transmitted by the lugs 7 to the ends of the limbs 5 so that these ends perform the same motions as the bolts 1 without pivoting.

Referring to Fig. 3, the full lines indicate diagrammatically the shape of the elastic neutral line of one of the substantially U-shaped straps in the non-energized condition of the transformer. Points P1 and P2 designate the ends of the limbs 5, which perform the same motions as the bolts 1. In the deformed condition these points take up positions P1 and P2 respectively on the line through P1 and P2. The members of the U-shaped straps may then be subjected to an elastic deformation such that the neutral line assumes the shape indicated by a broken line. In general the center M of the transverse part 6 will in this case experience a vertical shift to the position M.

The moments of inertia of the transverse part 6 and of the limbs 5 against the deformations described and the convergence of the limbs 5 are, however, such that this vertical shift of the center of the transverse member is very small and preferably equal to zero.

In a practical case a 200 VA transformer having a maximum inductance of 12,000 Gauss in the limb 2 of the transformer, each of the bolts performed periodic outward motions P1 to P'r and P2 to P2 of 0.1.31.1. in the horizontal plane through the bolts. The stay straps 4 were made from sheet iron 1.5 mm. in thickness. The limbs 5 were at an angle of 25 to one another. The length of the neutral line of the limbs 5 was about 35 mm., that of the neutral line of the transverse part about mm., the width of the limbs 5.5 mm. and that of the transverse part 15.0 mm. With the measuring apparatus employed the center of the transverse member did not exhibit a measurable periodic motion in any direction, i. e. the amplitude of this motion, if any, was less than 0005a.

If the width of the limbs is chosen to be 4.5 or 6.5 mm. instead of 5.5 mm., all the other dimensions being exactly the same, the periodic motion of the center of the transverse member is 0.012 in a downward direction for the 4.5 mm. and 0013 in an upward direction for the 6.5 mm. Downward direction as used herein means motion of the point M in a direction away from a horizontal line through the points P1 and P2. Upward direction means motion of the point M in a direction towards the horizontal line through the points P1 and P2. Fig. 3 illustrates the case where outward motion of the points P1 and P2 causes an upward motion of the point M to the position M. However, by a rearrangement of the rigidity of the various parts, the motion of the points P1 and P2 will actually cause a downward motion of the point M. It will be observed that this type of motion of the point M is not a harmonic vibration around a center rest position, but is actually a periodic displacement in 3 one direction by the point M, in the same manner that the points P1 and P2 onlymove outwardly from their initial position and do not vibrate about their initial position.

If, as an alternative, the width of the transverse member 6 or the angle between the limbs are increased with respect to the said values of 15 mm. or 25 respectively, all the other dimensions being exactly the same, the outward motion of the points P1 and P2 causes a downward motion of the center of the transverse member, whereas a decrease of these dimensions with respect to the said values has a reversed eifect.

It should be noted that, if the limbs 5 are at right angles to the transverse member 6, the outward motion of the points P1 and P2 invariably has the efiect of an upward motion of the center of the transverse member 6, which can be reduced to the limit value of O by an increase in rigidity of the transverse member or decrease in rigidity of the limbs, but in this case the value 0 can never be reached exactly, let alone, that the upward motion could be reversed into downward motion.

What we claim is:

1. The combination of electrical apparatus having an elongated member subject to self-energized oppositelydirected longitudinal vibrations and a fastening device securing said apparatus to a supporting body and spaced therefrom, said device comprising a substantially U-shaped member having a longitudinally-extending base and two upwardly extending straight limbs of substantially equal length each forming an angle of less than 90 with the base, the planes of said limbs converging toward each other to define at the intersection of said planes an angle in excess of 20, means securing the elongated member at portions thereof subject to oppositely-directed longitudinal vibrations to and between the extremities of said limbs, and means securing a central portion only of said base to said supporting body, the rigidity of the limbs and the base and the angle between the limbs being such that the central portion of said base is substantially motionless when said apparatus is energized.

2. The combination set forth in claim 1 wherein the planes of the limbs converge toward each other to define at their intersection an angle between about 20 and References Cited in the file of this patent UNITED STATES PATENTS 1,632,101 Thordarson June 14, 1927 1,666,889 Desloge Apr. 24, 1928 1,798,846 Kennedy Mar. 31, 1931 1,806,329 Brump May 19, 1931 2,018,180 Lawton Oct. 22, 1935 2,209,477 Reibel July 30, 1940 2,285,304 Reck June 2, 1942 2,460,682 Doughman Feb. 1, 1949 

